The present invention pertains generally to mechanical linkages. More particularly, the present invention pertains to mechanical linkages that allow for limited translational and rotational movement between the links. The present invention is particularly, but not exclusively, useful as a mechanical linkage for use in conjunction with an anti-sway bar on an oval track race car.
Anti-sway bars can be used to reduce the amount of body roll experienced by an automobile during turning while having a minimal effect on the suspension characteristics of an automobile during straight travel. A typical anti-sway bar consists of a torsion bar section and two anti-sway bar arms that extend laterally from each end of the torsion bar section. For all uses, the torsion bar section is attached to the automobile frame. When used on the front of an automobile, one of the anti-sway bar arms is attached to a control arm for one wheel, while the second anti-sway bar arm is attached to a control arm for the wheel on the other side of the automobile. Typically, rod ends having spherical bearings are used to connect the anti-sway bar arms to the control arms. During a turn, the frame and/or body of the automobile moves relative to the wheels and control arms (i.e. body roll) due to the centrifugal forces generated during the turn. During this roll, each sway bar arm rotates about the torsion bar section, causing the torsion bar section to twist. It is the resistance of the torsion bar section to this twisting force that reduces the amount of body roll experienced by an automobile during the turn.
One problem with anti-sway bars is their effect during a turn when one of the wheels encounters a bump or pothole. For example, consider an anti-sway bar equipped automobile that is turning to the left. As described above, during the turn, the anti-sway bar will be loaded, reducing the amount of body roll experienced by the automobile. It is known that when the left wheel encounters a bump or pothole, the loaded anti-sway bar will transmit a force to the right wheel due to the bump or pothole. Specifically, during a moderate to severe turn, the force transmitted to the right wheel is often sufficient to cause the right tire to lose traction and may even cause the right tire to leave the pavement. This loss of traction can affect the steering response of the automobile, and thus should be avoided.
Oval track race cars generally travel around the track in a counter-clockwise direction, and consequently, designers of oval track race cars are primarily concerned with reducing body roll during a left turn. Thus, a typical anti-sway bar reduces body roll equally in left turns and right turns, and is subject to traction loss during a turn that is often inappropriate for an oval track race car.
In light of the above, it is an object of the present invention to provide anti-sway bar systems capable of reducing body roll during a left turn while eliminating the transmission of forces through the anti-sway bar that reduce traction when the left wheel encounters a bump or pothole. It is another object of the present invention to provide a linkage between two members that allows for relative movement of the members in a chosen direction before forces carried by the members are transmitted across the linkage. Yet another object of the present invention is to provide a compensating linkage which is easy to use, relatively simple to manufacture, and comparatively cost effective.
The present invention is directed to a mechanical link for attaching a first load-carrying member such as a sway bar arm to a second load-carrying member such as a control arm for the front wheel of an oval track race car. For the present invention, the mechanical link includes at least one ball and an elongated race that defines an axis. The ball is provided for attachment to the first load-carrying member and engagement with the race, while the race is provided for attachment to the second load-carrying member.
The elongated race is formed with an aperture that is surrounded by two opposed faces and two opposed semi-circular surfaces. As such, the opposed faces are connected to each other by the opposed semi-circular surfaces. Importantly, each face is formed with a channel that extends in a direction that is substantially parallel to the direction of the axis of the race. Preferably, each channel has a circular cross-sectional shape normal to the direction of the channel. Additionally, each semi-circular surface is formed with a channel extending along each semi-circular surface to connect the channel on one face to the channel on the other face. As such, the aperture of the race is surrounded by one continuous channel that extends along each face and along each semi-circular surface. Preferably, the continuous channel has a substantially constant radius of curvature, rchannel, normal to the direction of the channel. For the present invention, the closest distance between the opposed faces is designated, daperture, min, and the farthest distance between the opposed faces is designated, daperture, max.
The link further includes at least one ball having a substantially spherical outer surface of radius, rball. For the present invention, the ball is sized to have a radius, rball, that is equal or slightly smaller than the radius of curvature of the channel, rchannel. Preferably, the ball is formed with a cylindrical thru-hole that passes through the center of the ball. As such, two circular openings are provided for the thru-hole that are separated by a distance, dball, min. For the present invention, the ball and thru-hole are sized such that dball, min is less than daperture, min. Further, the ball and thru-hole are sized such that the diameter of the ball (i.e. 2xc3x97rball) is greater than daperture, min but less than daperture, max.
With this cooperation of structure, the ball can be engaged with the race to provide a mechanical link when the first load-carrying member is attached to the ball and the second load-carrying member is attached to the race. Specifically, with this cooperation of structure, the ball can be disposed within the aperture of the race by first positioning the ball adjacent to the race with the circular openings of the thru-hole aligned with the opposed faces of the race aperture. With this alignment, the ball can be inserted into the aperture, since dball, min is less than daperture, min. Next, the ball can be rotated until the circular openings of the thru-hole are aligned roughly perpendicular to the opposed faces of the race aperture since the quantity (2xc3x97rball) is less than daperture, max, and rball is equal or slightly smaller than the radius of curvature of the channel, rchannel. In this alignment, the ball is confined within the aperture of the race since the quantity (2xc3x97rball) is greater than daperture, min.
Once the ball is confined within the aperture of the race, the first load-carrying member can be attached to the ball. Preferably, the first load-carrying member is formed with a cylindrical protrusion that can be engaged with the thru-hole of the ball. Specifically, it is contemplated for the present invention that the cylindrical protrusion on the first load-carrying member can be inserted into one of the circular openings of the thru-hole until the cylindrical protrusion projects from the other circular opening of the thru-hole. Once inserted in this manner, the cylindrical protrusion can be secured to the ball by pressing a quick-release pin through a passageway formed in the portion of the cylindrical protrusion that projects from the thru-hole.
It is to be appreciated that once the first load-carrying member is attached to the ball as described above, the ball will be unable to rotate into a position where the circular openings of the thru-hole are aligned with the opposed faces of the race aperture. Consequently, once the first load-carrying member is attached to the ball, the ball will be confined within the aperture of the race. It is to be further appreciated that although the ball is confined within the aperture of the race the ball is free to translate within the aperture and along the axis of the race. Additionally, with this combination of structure, the ball will enjoy a limited amount of rotation about the center of the ball. It is to be appreciated that the exact amount of rotation enjoyed by the ball will depend on the dimensions of the ball, the race and the first member, and that the rotation of the ball will be limited by contact between the first member and the race.
In one embodiment of the present invention, the race is formed with an extension in addition to the portion of the race that surrounds the elongated aperture. Preferably, the extension projects axially from the race portion that surrounds the aperture and is formed with a recess. For the present invention, a portion of the second member can be inserted into the recess to allow for direct attachment of the race to the second member. This location for the extension on the race allows for attachment of the second member to the race without limiting the movement of the ball and first member in the aperture of the race.
In another embodiment for the present invention, two identical balls are disposed within the aperture of the race, with each ball having the features described above. The first ball is attached to the first load-carrying member and the second ball is attached to the second load-carrying member. Each ball is attached to the corresponding load-carrying member as described above. As such, each ball is free to translate within the aperture and along the axis of the race, and each ball will enjoy a limited amount of rotation. It is to be appreciated that the amount of translation each ball will have will be limited by the presence of the other ball.